System and method for spine fusion using an expandable cage

ABSTRACT

An expandable cage system for use in spinal surgery includes a top portion having an outwardly extending top arm, and a bottom portion having an outwardly extending bottom arm. The bottom arm is configured to engage with the top arm such that upon engagement, the top portion and the bottom portion are substantially restricted from movement relative to each other in an anterior-posterior direction, and in a medial-lateral direction. The expandable cage system further includes a removable shim configured to be positioned between the top portion and the bottom portion to hold the expandable cage in an expanded position within a spinal cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/431,292 filed on Feb. 13, 2017, which claims priority toU.S. Provisional Patent App. No. 62/297,852 filed on Feb. 20, 2016, theentireties of which are incorporated by reference herein.

BACKGROUND

The following description is provided to assist the understanding of thereader. None of the information provided or references cited is admittedto be prior art.

The lumbar spine refers to the lower back, and is where a human's spinalcolumn curves inward toward the abdomen. The lumbar spine, whichtypically starts five to six inches below the shoulder blades, connectswith the thoracic spine at the top and the sacral spine at the bottom. Ahuman lumbar spine typically includes five vertebrae, although someindividuals have four or six vertebrae in their lumbar spine. There areseveral different conditions that can affect the lumbar spine and causepain, including disk problems, scoliosis and other spinal deformities,spondylolisthesis, stenosis, tumors, and fractures. These conditions mayresult from trauma, disease, and degenerative conditions caused byaging, injury, or may be idiopathic. Non-operative treatments such asphysical therapy, medications, exercise, and/or injections may or maynot relieve the symptoms associated with these disorders. Surgery may beused to help alleviate pain in some individuals who are suffering fromdisk problems and other ailments. Surgery may include decompression ofthe neural elements, correction of deformity, removal of disk material,instrumentation, and/or implantation of prosthetic devices.

SUMMARY

In accordance with at least some aspects of the present disclosure, anexpandable cage system for use in spinal surgery is disclosed. Theexpandable cage system includes a top portion having an outwardlyextending top arm, and a bottom portion having an outwardly extendingbottom arm. The bottom arm is configured to engage with the top arm suchthat upon engagement, the top portion and the bottom portion aresubstantially restricted from movement relative to each other in ananterior-posterior direction, and in a medial-lateral direction. Theexpandable cage system further includes a removable shim configured tobe positioned between the top portion and the bottom portion to hold theexpandable cage in an expanded position within a spinal cavity.

In accordance with at least some other aspects of the presentdisclosure, a method is disclosed. The method includes inserting anexpandable cage within a spinal cavity, and expanding the expandablecage to an expanded position within the spinal cavity. The expandingincludes moving a top portion of the expandable cage away from a bottomportion of the expandable cage using an expansion device. The methodfurther includes inserting a first shim and a second shim within theexpandable cage and between the top portion and the bottom portion forholding the expandable cage in the expanded position. The methodadditionally includes removing the expansion device.

In accordance with yet other aspects of the present disclosure, anothermethod is disclosed. The method includes inserting an expandable cage ina contracted position within a spinal cavity, such that the expandablecage includes a top portion engaged with a bottom portion. The methodalso includes positioning the expandable cage between a first vertebraand a second vertebra, expanding the top portion relative to the bottomportion for obtaining an expanded position for facilitating fusion ofthe first vertebra and the second vertebra, and inserting a shim betweenthe top portion and the bottom portion for holding the expandable cagein the expanded position.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the following drawings and thedetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view depicting a top surface of a top portionof a lateral extrinsically expandable cage, in accordance with anillustrative embodiment.

FIG. 1B is a perspective view depicting a bottom surface of the topportion of the expandable cage, in accordance with an illustrativeembodiment.

FIG. 1C is a perspective view of a bottom portion of the expandablecage, in accordance with an illustrative embodiment.

FIG. 2 is a perspective view depicting the top portion and the bottomportion of the expandable cage in an assembling position, in accordancewith an illustrative embodiment.

FIG. 3 is a perspective view depicting the top portion and the bottomportion of the expandable cage in another assembling position, inaccordance with an illustrative embodiment.

FIG. 4 is a perspective view depicting shims that hold the expandablecage in an expanded position, in accordance with an illustrativeembodiment.

FIG. 5A is a perspective view depicting the top portion and the bottomportion of the expandable cage in an engaged position, with the shimsinserted to expand the expandable cage to a first height, in accordancewith an illustrative embodiment.

FIG. 5B is a perspective view depicting the top portion and the bottomportion of the expandable cage in an engaged position, with the shimsinserted to expand the expandable cage to a second height, in accordancewith an illustrative embodiment.

FIG. 6A is a perspective view depicting the shims in an assemblingposition within the bottom portion of the expandable cage, and with thetop portion dis-engaged from the bottom portion, in accordance with anillustrative embodiment.

FIG. 6B is a perspective view depicting the shims in an assembled formwithin the bottom portion of the expandable cage, and with the topportion dis-engaged from the bottom portion, in accordance with anillustrative embodiment.

FIG. 7 is a top perspective view depicting the shims in the assembledform in the bottom portion of the expandable cage, in accordance with anillustrative embodiment.

FIG. 8A is a perspective view depicting the bottom portion of theexpandable cage, in accordance with another illustrative embodiment.

FIG. 8B is another perspective view depicting the bottom portion of theexpandable cage of FIG. 8A, in accordance with another illustrativeembodiment.

FIG. 8C is a perspective view depicting the top portion of theexpandable cage, in accordance with another illustrative embodiment.

FIG. 9A is a perspective view depicting the top portion and the bottomportion of the expandable cage in an engaged position, with theexpandable cage expanded and prior to inserting the shims, in accordancewith another illustrative embodiment.

FIG. 9B is a perspective view depicting the top portion and the bottomportion of the expandable cage in an engaged position, with theexpandable cage expanded and with the shims inserted, in accordance withanother illustrative embodiment.

FIG. 10 is a perspective view depicting the top portion and the bottomportion of the expandable cage in an engaged position, with the shimsremoved and the expandable cage maximally contracted in height, inaccordance with another illustrative embodiment.

FIG. 11 is a perspective view depicting the top portion and the bottomportion of the expandable cage, in accordance with yet anotherillustrative embodiment.

FIG. 12A is a perspective view depicting the top portion and the bottomportion of the expandable cage in an engaged position, with theexpandable cage expanded and prior to inserting the shims, in accordancewith yet another illustrative embodiment.

FIG. 12B is a perspective view depicting the top portion and the bottomportion of the expandable cage in an engaged position, with theexpandable cage expanded and the shims inserted, in accordance with yetanother illustrative embodiment.

FIG. 12C is a side perspective view depicting the top portion and thebottom portion of the expandable cage in an engaged position, with theexpandable cage expanded and the shims inserted, in accordance with yetanother illustrative embodiment.

FIG. 13 is a perspective view depicting the top portion and the bottomportion of the expandable cage having features configured to attach acage insertion and expansion device, in accordance with an illustrativeembodiment.

FIG. 14A is a perspective view depicting the expandable cage and theinsertion and expansion device in an assembly position, in accordancewith an illustrative embodiment.

FIG. 14B is a perspective view depicting the expandable cage and theinsertion and expansion device in an assembled position, prior toinsertion of fasteners, in accordance with an illustrative embodiment.

FIG. 14C is a perspective view depicting the expandable cage and theinsertion and expansion device in an assembled position, with fastenerssecuring the expandable cage to the insertion and expansion device, inaccordance with an illustrative embodiment.

FIG. 14D is a perspective close-up partial view depicting the expandablecage and the insertion and expansion device in an assembled position,prior to insertion of fasteners, in accordance with an illustrativeembodiment.

FIG. 14E is a top perspective view depicting the expandable cage and theinsertion and expansion device and the fasteners in an assemblyposition, in accordance with an illustrative embodiment.

FIG. 14F is a top perspective view depicting the expandable cage and theinsertion and expansion device and the fasteners in an assembledposition, with fasteners securing the expandable cage to the insertionand expansion device, in accordance with an illustrative embodiment.

FIG. 14G is a side perspective view depicting the expandable cage andthe insertion and expansion device and the fasteners in an assembledposition, with fasteners securing the expandable cage to the insertionand expansion device, in accordance with an illustrative embodiment. Thecage is depicted in a collapsed or contracted configuration.

FIG. 14H is a side perspective view depicting the expandable cage andthe insertion and expansion device and the fasteners in an assembledposition, with fasteners securing the expandable cage to the insertionand expansion device, in accordance with an illustrative embodiment. Thecage is depicted in an expanded configuration.

FIGS. 15A-15C are lateral or side views of a portion of a lumbar spinewith the expandable cage inserted and positioned in an interbody space,with FIG. 15A depicting the expandable cage in the collapsed orcontracted configuration, FIG. 15B depicting the expandable cage in anexpanded configuration, and FIG. 15C depicting the expandable cage in anexpanded configuration with the shims inserted for holding theexpandable cage in an expanded configuration, in accordance withillustrative embodiments.

FIG. 16 is an anterior or front view of a portion of the lumbar spinewith the expandable cage inserted and positioned in the interbody space,in accordance with an illustrative embodiment.

FIG. 17 is a flowchart outlining a process of using the expandable cage,in accordance with an illustrative embodiment.

The foregoing and other features of the present disclosure will becomeapparent from the following description and appended claims, taken inconjunction with the accompanying drawings. Understanding that thesedrawings depict only several embodiments in accordance with thedisclosure and are, therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, and designed in awide variety of different configurations, all of which are explicitlycontemplated and make part of this disclosure.

A lateral, or alternatively anterolateral lumbar spine fusion(collectively referred to as “spine fusion” herein) is typicallyperformed through one or more incisions placed on a lateral oranterolateral portion of a human abdomen. The incision(s) are just largeenough to accommodate a retractor device that allows visualization ofthe human spine. The spine is typically approached through aretroperitoneal space in the abdominal cavity. Upon exposing the spinaldisk to be fused, a diskectomy or other surgical treatments may beperformed through standard techniques well known to those of skill inthe art. As part of the diskectomy or the other surgical treatments,intervertebral or structural cages may be inserted into a disk space orspinal cavity of the spine to correct spinal deformity, to stabilize thespine, and/or to deliver biological material to promote a bony fusionbetween two vertebral bodies of the spine.

Specifically, once the diskectomy is performed, vertebral endplates areprepared for the bony fusion, and a structural bone graft or astructural cage containing a bone growth promoting substance such as abone graft is placed into the intervertebral space. The structural cagetypically provides structural support between the vertebral bodies thatare to be fused. The structural cage may be optionally held in placewith a variety of techniques, including an interference screw, screwsthat are integrated into a plate, or with a plate that may be attachedto or be separate from the structural cage.

The structural cage that is placed in the intervertebral space may bestatic or dynamic. A static cage has fixed dimensions that aredetermined upon manufacture of the static cage. In contrast, anexpandable cage is dynamic and may be inserted into the intervertebralspace prior to expansion, and then expanded once the expandable cage isin position. Some of the benefits of an expandable cage compared to astatic cage are ease of insertion because the expandable cage may beinserted in a lowest height profile (or in other words, in a maximallycontracted position) of the expandable cage, and then expanded to thedesired height after insertion, thereby reducing trauma to the vertebralendplates during insertion. Additionally, an expandable cage has theability to expand to a taller overall cage height because cage insertionis less traumatic to the vertebral endplates. A drawback of anexpandable cage compared to a static cage is the mechanism by which thecage is expanded. Conventionally, the expandable cage is expandedintrinsically and the intrinsic mechanism used to expand the expandablecage becomes a permanent part of the expandable cage. Therefore, theintrinsic mechanism occupies space within the expandable cage anddecreases the amount of the bone growth promoting substance (e.g., bonegraft) that may be placed within the expandable cage.

Additionally, the intrinsic mechanism used to expand the expandable cageafter insertion adds technical complexity to the overall process. Theintrinsic mechanism also increases the overall cost of the expandablecage, and potentially becomes a site of mechanical weakness. The presentdisclosure overcomes at least some of these disadvantages by providing asurgical system that combines the benefits of an expandable cage withthe simplicity of a static cage. Specifically, the surgical system ofthe present disclosure provides a spinal construct including a lateralextrinsically expandable cage, and components related to the expandablecage, and its surgical implantation. The expandable cage may be expandedusing an extrinsic mechanism upon implantation in the intervertebraldisk space or spinal cavity.

In particular, the expandable cage of the present disclosure includesfour primary components—a top portion, a bottom portion, a first shim,and a second shim. The top portion and the bottom portion of the cageare configured to mate or engage together in a manner that restrictsmovement of the top portion with respect to the bottom portion inanterior-posterior (e.g., front-back) and medial-lateral (e.g., leftsside-right side) directions. The expandable cage is further configuredto be expanded in a cephalad-caudal (e.g., vertical or top-bottom)direction, thereby making the expandable cage taller after installation.

The expandable cage may be expanded extrinsically using an extrinsic(e.g., outside the spinal cavity) removable insertion and expansiondevice configured to hold the expandable cage in an assembled andexpanded state while the first shim and the second shim are inserted.Specifically, the insertion and expansion device is configured to attachto the expandable cage, and facilitate insertion and positioning of theexpandable cage within the spinal cavity. After insertion, the insertionand expansion device temporarily holds the top portion relative to thebottom portion in an expanded position to facilitate insertion of theshims. The first shim and the second shim are then inserted within theexpandable cage to hold the expandable cage in the expanded form. Theinsertion and expansion device is removed upon inserting the first shimand second shim within the expandable cage. Shims of different heightsmay be utilized to control the overall height and shape of theexpandable cage.

By virtue of using the surgical system of the present disclosure, theexpandable cage may be used to treat spinal conditions such as, forexample, stenosis, spondylolisthesis, scoliosis, kyphosis, otherdeformities, trauma, tumor, infection, disk herniation, and degenerativedisk disease. The expandable cage may also be used for fusion in thethoracic or lumbar spine, and across the thoracolumbar and lumbosacraljunctions. The expandable cage may additionally be employed for surgicaltreatments in a patient in a lateral, supine, oblique, or proneposition, and may employ various approaches to the spine, includinganterior, anterolateral, and lateral. The expandable cage may be used,in addition to humans, on animals, bone models, and other non-viablesubstrates, for example, for use in testing, demonstration, andtraining.

Referring now to FIGS. 1A-1C, perspective views depicting an expandablecage 100 are shown, in accordance with illustrative embodiments. Theexpandable cage 100 includes a top portion 105 (see FIGS. 1A-1B) and abottom portion 110 (see FIG. 1C). The top portion 105 is also referredto herein as top part, upper part/portion, and superior part/portion,and the bottom portion 110 is also referred to herein as bottom part,lower part/portion, and inferior part/portion.

With specific reference to FIGS. 1A and 1B, the top portion 105 of theexpandable cage 100 includes a top surface 115 (also referred to hereinas uppermost surface) and a bottom surface 120 (also referred to hereinas undersurface). The top surface 115 of the top portion 105 isconfigured to engage an inferior endplate of an upper vertebral body ina spinal fusion surgical procedure, while the bottom surface 120 of thetop portion is configured to align the expandable cage 100 in an upsidedown position after surgical implantation. Although the top portion 105and the bottom portion 110 have been shown as being generallyrectangular in shape, in other embodiments, the top portion and thebottom portion may assume other shapes and sizes. In some embodiments,the expandable cage 100 may be approximately forty to sixty millimeters(40-60 mm) in medial-to-lateral length, fifteen to twenty fivemillimeters (15-25 mm) in anterior-posterior width, and six to thirtymillimeters (6-30 mm) in superior-to-inferior height. In otherembodiments, one or more of the dimensions of the expandable cage 100may vary depending upon the patient anatomy in which the expandable cageis used.

The top portion 105 includes arms 125 and 130 (also referred to hereinas posts or top arms) that project outwardly from the bottom surface 120of the top portion. In some embodiments, the arms 125 are provided at oradjacent to the four corners of the top portion 105. Furthermore, insome embodiments, the arms 125 are configured as single outwardprojections. Also, in some embodiments, the arms 130 are providedequidistant (or substantially equidistant) between the arms 125, and areconfigured with three outward projections aligned at ninety degrees toeach other, thereby creating a slot 135. The slot 135 is configured toreceive and mate (e.g., engage) with corresponding arms 140 (see FIG.1C) extending outwardly from the bottom portion 110. By virtue ofreceiving the arms 140, the arms 130 confine the movement of the arms140, thereby facilitating assembly or engagement of the top portion 105to the bottom portion 110, and restricting movement of the expandablecage 100 in the anterior-posterior and medial-lateral directions.Notwithstanding that four of the arms 125 and two of the arms 130 areshown in FIGS. 1A and 1B, in other embodiments, greater than or fewerthan four arms for the arms 125, and greater than or fewer than two armsfor the arms 130, may be provided in the top portion 105. Additionally,the shape, size, orientation, and other configuration of the arms 125and the arms 130 may vary in other embodiments.

The directions anterior-posterior, and medial-lateral are wellunderstood terms to people of skill in the art. For example, ananterior-posterior direction may refer to a horizontal, substantiallyhorizontal, front-back, or back-front direction (e.g., rib-spine orspine-rib direction of a human body), while a medial-lateral directionmay refer to a horizontal, substantially horizontal, left-right, orright-left direction (e.g., left hand-right hand or right hand-left handdirection of a human body). Similarly, a cephalad-caudal direction or asuperior-inferior direction may refer to a vertical, substantiallyvertical, top-bottom, or bottom-top direction (e.g., head-toe ortoe-head direction of the human body). Generally speaking, as usedherein, the anterior-posterior and medial-lateral directions refer tomotion that offsets the top portion 105 relative to the bottom portion110 (e.g., at an angle) without impacting (or substantially impacting)the distance or height between the top portion and the bottom portion.Likewise, the cephalad-caudal direction or superior-inferior directionsrefer to motion that varies the distance (e.g., height) between the topportion 105 and the bottom portion 110 without offsetting (orsubstantially offsetting) the angle of the top portion relative to thebottom portion.

Referring now to FIG. 1C in conjunction with FIGS. 1A and 1B, the bottomportion 110 additionally includes arms 145 that project outwardly from abottom surface 153 of the bottom portion. The arms 145 are situated ator adjacent to the four corners of the bottom portion 110, and areconfigured to engage (e.g., abut) the arms 125 upon assembly orengagement. In some embodiments and as shown, the arms 140 and the arms145 are similar in configuration, or in alternative embodiments, thosearms may be configured differently from each other. Additionally,similar to the arms 125 and the arms 130, the arms 140 and the arms 145may vary in shape, size, orientation, and configuration from oneembodiment to another, so long as the arms 125 are configured to mate(e.g., engage) with the arms 145, and the arms 140 are configured tomate (e.g., engage) with the arms 130.

The top portion 105 and the bottom portion 110 of the expandable cage100 also include an opening 150, in some embodiments, to allow a bonegraft promoting material (e.g., bone graft) to be placed within thatopening. By placing the bone graft promoting material within the opening150, the expandable cage 100 allows the bone graft promoting material tocome into contact with adjacent vertebral endplates to facilitate fusionthereof. The shape, size, and configuration of the opening 150 may varyin other embodiments from that shown. In some embodiments, the shape,size, and configuration of the opening 150 on the top portion 105 mayvary from the shape, size, and configuration of the opening on thebottom portion 110. In yet other embodiments, the opening 150 may beabsent altogether.

In alternative embodiments, the arms 125, 130, 140, and 145 may beconfigured to articulate via a hinge or similar rotatory component withrespect to the top portion 105 and the bottom portion 110. In thismanner, shims (see FIG. 4) of different heights anteriorly andposteriorly may be placed, resulting in a cage (e.g., the expandablecage 100) with a taller height anteriorly than posteriorly, or a tallerheight posteriorly than anteriorly, which may result in the cageassuming a lordotic or kyphotic configuration, thereby enabling asurgeon to control, to some degree, a patient's sagittal alignmentduring a surgical treatment.

Furthermore, the bottom portion 110 includes, in some embodiments,outward projections 155 and 160 to create grooves 170. In someembodiments, the grooves 170 may be bound on one end by end projections175 that connect the outward projections 155 and 160. In someembodiments, the expandable cage 100 may be positioned during insertionsuch that openings 180 (e.g., the end of the grooves 170 that isopposite to the end projections 175) face the lateral surgical incisionto accommodate a shim (See FIG. 4) within the grooves, and the endprojections are facing opposite to the lateral incision. The endprojections 175 prevent the shim from being over-inserted (e.g., fromextending beyond the profile of the expandable cage 100). In alternativeembodiments, the grooves 170 may be surrounded by walls on all foursides by the presence of an additional end projection instead of theopenings 180. Furthermore, in some embodiments, corresponding groovesmay be provided on the top portion in addition to, or instead of, thegrooves 170 on the bottom portion 110. Additionally, in someembodiments, each of the grooves 170 may be of varying widths. In someembodiments, the grooves 170 may be configured based upon theconfiguration of the shims that those groves are designed to receive. Atop surface (e.g., the surface opposite the bottom surface 153) of thebottom portion 110 is configured to engage a superior endplate of thelower vertebral body in a spinal fusion.

Turning now to FIG. 2, a perspective view depicting the top portion 105and the bottom portion 110 of the expandable cage 100 in an assemblingposition is shown, in accordance with illustrative embodiments. Asdiscussed above, the arms 125 and the arms 130 project outwardly fromthe top portion 105, and are configured to mate (e.g., engage) with thearms 145 and 140, respectively, of the bottom portion 110. Specifically,in some embodiments, the arms 125 of the top portion 105 are configuredsuch that upon engaging the arms 145 of the bottom portion 110, the arms125 rest upon the outward projections 155 in a maximally contractedposition (e.g., when the top portion is engaged with the bottom portion,but before inserting of shims, discussed below). Similarly, the arms 130of the top portion 105 are configured such that upon engaging the arms140 of the bottom portion 110, the arms 140 fit within the slot 135 ofthe arms 130. For example, in some embodiments, the arms 145 may beconfigured to slide within the slot 135, in a relationship explainedfurther below in FIG. 3.

Furthermore, in some embodiments, at least some of the arms 125 includea lip 185 to prevent a shim (See FIG. 4) from migrating after insertioninto the grooves 170. In some embodiments, the lip 185 may be providedon those ones of the arms 125 that upon engagement with the arms 145correspond to the openings 180 (e.g., opposite the end projections 175).Thus, the lip 185, along with the end projections 175, prevents the shimfrom sliding out of the grooves 170 after being inserted, or in otherwords, restricts motion of the shim within the grooves. In otherembodiments, the lip 185 may be absent. For example, in thoseembodiments where the openings 180 are provided with end projectionssimilar to the end projections 175, the lip 185 may not be needed. Inyet other embodiments, all of the arms may be configured with the lip185, and the end projections 175 may not be needed.

Furthermore, as discussed above, in some embodiments, the outwardprojections 155 and 160 from the bottom surface 153 of the bottomportion 110 create the grooves 170 that are configured to accommodateshims, shown and discussed below in FIG. 4. In some embodiments, theexpandable cage 100 may be positioned during insertion into the spinalcavity such that the grooves 170 may be open (e.g., via the openings180) on the side of the expandable cage 100 facing the lateral surgicalincision, and the end projections 175 may be located on the side of theexpandable cage 100 opposite the lateral incision and prevent the shimfrom being over-inserted (e.g., sliding out of the grooves 170). Inalternative embodiments, the grooves 170 may be surrounded by walls onall four sides by the presence of an additional outward projection fromthe bottom surface 153 of the bottom portion 110 of the expandable cage100, located on the side of the expandable cage facing the lateralsurgical incision (e.g., in the openings 180).

Referring now to FIG. 3, a perspective view depicting the top portion105 and the bottom portion 110 of the expandable cage 100 in anotherassembling position is shown, in accordance with illustrativeembodiments. Specifically, in some embodiments, when the top portion 105is engaged or mated with the bottom portion 110 via the arms 125, 130,140, and 145, the arms 130 form the slot 135 that receives the arms 140,thus restraining movement of the top portion with respect to the bottomportion in the anterior-posterior and medial-lateral directions,allowing only cephalad-caudal expansion or contraction of the topportion with respect to the bottom portion. Specifically, when the topportion 105 is engaged or mated with the bottom portion 110, the arms125 are adjacent to (e.g., abut) the arms 145, further restrainingmovement of the top portion with respect to the bottom portion in theanterior-posterior direction, but allowing cephalad-caudal expansion orcontraction of the top portion with respect to the bottom portion.

Additionally, when the expandable cage 100 is inserted into theintervertebral disk space or spinal cavity during an operation, the sidemarked “A” on FIG. 3 faces anteriorly, the side marked “P” facesposteriorly, the side marked “L1” faces the lateral side of the patienttowards the incision, and the side marked “L2” faces the lateral side ofthe patient opposite the side of the incision.

Turning now to FIG. 4, example shims 190 and 195 are shown, inaccordance with illustrative embodiments. In some embodiments, the shims190 and 195 are rectangular in shape and have same (or similar) length,L, and same (or similar) width, W, but vary in height, D1 and D2.Generally speaking, the length, L, of the shim 190 and the shim 195corresponds substantially to the length of the bottom portion 110 and,particularly, to the length of the grooves 170 of the bottom portion.Likewise, the width, W, of the shim 190 and the shim 195 may vary basedupon the width of the grooves 170.

With respect to the height, D1, of the shim 190, and the height, D2, ofthe shim 195, by varying the height of those shims, the height of theexpandable cage 100 may be varied upon expansion. In some embodiments,two of the shims (e.g., two of the shim 190 or two of the shim 195) maybe used to expand the expandable cage 100 to an expanded position. Inother embodiments, greater than or fewer than two of the shims may beused. Further, the location of the shims (e.g., the shim 190 and theshim 195) and, therefore, the location of the grooves 170 on the bottomportion 110 of the expandable cage 100 may vary in other embodiments.Additionally, in some embodiments, each of the two shims that is usedfor expanding the expandable cage 100 have the same or similar height.In other embodiments, it may be desirable to have those shims be ofvarying heights. Thus, the configuration of the shims (e.g., the shim190 and the shim 195), the number of shims used, and the location of theshims within the expandable cage 100 may vary from one embodiment toanother.

As an example, the height, D1, of the shim 190 is shown taller than theheight, D2, of the shim 195. Thus, by replacing the shim 190 with theshim 195, or vice-versa, the height of the expandable cage 100 may beadjusted for adjusting the final cage configuration and height.

Referring now to FIG. 5A, a perspective view depicting the expandablecage 100 in a final, fully engaged and expanded form after surgicalimplantation in a patient is shown, in accordance with illustrativeembodiments. An instance of the shim 190 is inserted into each of thegrooves 170 that are formed by the outward projections 155 and 160, aswell as the end projections 175. In some embodiments, an instance of theshim 190 is inserted into each of the grooves 170 after the insertion ofthe expandable cage 100 into the spinal cavity. In other embodiments,the shims 190 may be inserted into the expandable cage 100 beforeinserting the expandable cage into the spinal cavity. After theinsertion of the shim 190 into the grooves 170, the lip 185 of the arms125 of the top portion 105 engages with the shim on the side of theopenings 180, and combined with the end projections 175 on the oppositelateral side of the grooves, constrain the shim and prevent migration ofthe shim in lateral directions. Additionally, in some embodiments, afterinsertion of the shim 190, a bottom surface (e.g., inferior-mostsurface) of the arms 125 rests upon a top surface (e.g., superior-mostsurface) of the shim 190, thus supporting the top portion 105 of theexpandable cage 100.

Furthermore, in some embodiments, when the top portion 105 is engaged ormated with the bottom portion 110, the slot 135 of the arms 130 receivesthe arms 140, thus restraining movement of the top portion with respectto the bottom portion in the anterior-posterior and medial-lateraldirections, allowing only cephalad-caudal expansion or contraction ofthe top portion with respect to the bottom portion. In some embodiments,when the top portion 105 is engaged or mated with the bottom portion110, the arms 125 are adjacent to the arms 145, thus restrainingmovement of the top portion with respect to the bottom portion in theanterior-posterior direction, but allowing for cephalad-caudal expansionor contraction of the top portion with respect to the bottom portion.Upon assembling the top portion 105 with the bottom portion 110, in anexpanded position, the width of the expandable cage 100 is W1 and thelength is L1. The final height, H1, of the expandable cage 100 isadjustable and determined by the height of the shim 190. In someembodiments, depending on the clinical circumstances, the expandablecage 100 may be implanted after being rotated 180 degrees in thevertical plane, such that the bottom portion 110 of the expandable cageis located cephalad to the top portion 105 of the expandable cage.

Thus, a lateral extrinsically expandable cage (e.g., the expandable cage100) includes four main parts: the top portion 105, the bottom portion110 configured to mate with the top portion, and two shims (e.g., twoinstances of the shim 190 or two instances of the shim 195) that areinserted into the grooves 170 on the bottom portion, and hold theexpandable cage in an expanded position of a variable height dependingprimarily on the height of the shims.

Referring to FIG. 5B, another perspective view depicting the expandablecage 100 in a final, fully engaged and expanded form after surgicalimplantation in a patient is shown, in accordance with illustrativeembodiments. FIG. 5B is similar to FIG. 5A, but uses the shim 195 thatis smaller in height than the shim 190 for adjusting the height of theexpandable cage 100. Again, the top portion 105 is engaged or mated withthe bottom portion 110, and the shim 195 is inserted into the grooves170 for assembling the expandable cage 100. Upon assembly, the finalheight, H2, of the lateral extrinsically expandable cage (e.g., theexpandable cage 100) of FIG. 5B is less than the final height, H1, ofthe lateral extrinsically expandable cage of FIG. 5A. However, thelength, L2, of the expandable cage 100 of FIG. 5B is the same as thelength, L1, of the expandable cage of FIG. 5A. Likewise, the width, W2,of the expandable cage 100 of FIG. 5B is the same as the width, W2, ofthe expandable cage of FIG. 5A. Thus, by varying the height of the shims(e.g., the shim 190 or the shim 195), the height, or the distancebetween the top portion 105 and the bottom portion 110, of theexpandable cage 100 may be varied.

Turning to FIGS. 6A and 6B now, perspective views of the top portion 105and the bottom portion 110 of the expandable cage 100 depictinginsertion of shims 190A and 190B into the bottom portion are shown, inaccordance with illustrative embodiments. Specifically, the perspectiveview of FIGS. 6A and 6B show the top portion 105 and the bottom portion110 not engaging (e.g., separate from) each other to illustrate theinsertion of the shims 190A and 190B into the bottom portion. It is tobe understood that the top portion 105 is shown as being un-assembledfrom the bottom portion 110 to only illustrate the insertion of theshims 190A and 190B. In some embodiments, the shims 190A and 190B mayindeed be inserted into the grooves 170 before assembling the topportion 105 to the bottom portion 110. In other embodiments, however,the top portion 105 may be assembled with the bottom portion 110 beforethe shims 190A and 190B are inserted into the grooves 170. As will bediscussed below, an insertion and expansion device may be used to holdthe top portion 105 in an expanded position relative to the bottomportion 110 to facilitate the insertion of the shims 190A and 190B.

FIG. 6A shows the shim 190A as partially inserted into the grooves 170for purposes of illustration, and the shim 190B as fully inserted intothe grooves. FIG. 6B shows both the shims 190A and 190B as fullyinserted into the grooves 170. Furthermore, in some embodiments, theshims 190A and 190B are identical to each other, and are configured tobe received (e.g., by sliding) within the grooves 170. In otherembodiments, the shims 190A and 190B may be of varying configurations.Also, in some embodiments, each of the grooves 170 may be of varyingconfigurations (e.g., of varying widths). In those instances, the shims190A and 190B may be of different configurations to correspond to theconfiguration of the respective one of the grooves 170 in which they areconfigured to be received.

Turning now to FIG. 7, a perspective view of the bottom portion 110 isshown, in accordance with an illustrative embodiment. The perspectiveview of FIG. 7 shows the shims 190A and 190B inserted into the grooves170. Specifically, the shims 190A and 190B may be inserted into thegrooves 170 by sliding the shims via the openings 180 into the groovesuntil the shims make contact with the end projections 175. Thus, theshims 190A and 190B sit within the grooves 170, and are bound by theoutward projections 155 and 160, the end projections 175, and the lip185 of the top portion 105 upon assembly. The outward projections 155and 160, the end projections 175, and the lip 185 constrain the movementof the shims 190A and 190B within the grooves 170. Although the shims190A and 190B have been shown in the present embodiment as extendingacross the entire (or substantially entire) length (e.g., length, L1 andL2) of the expandable cage 100, in other embodiments, either or both ofthose shims may be smaller in length and may span only a portion of thelength of the expandable cage. Furthermore, to accommodate the shims190A and 190B that are only a portion of the length of the expandablecage 100, the grooves 170 may or may not be of correspondingly smallerlength. In some embodiments, each of the grooves 170 may be of differentlengths to accommodate the shims 190A and 190B that are of differentlengths. Thus, various configurations of the shims 190A and 190B, aswell as of the grooves 170 are contemplated and considered within thescope of the present disclosure.

Referring now to FIGS. 8A-8C, perspective views depicting an alternativeembodiment of an expandable cage 200 are shown, in accordance withillustrative embodiments. Specifically, FIGS. 8A and 8B show aperspective view of a bottom portion 205 and FIG. 8C shows a perspectiveview of a top portion 210 of a lateral extrinsically expandable cage(e.g., the expandable cage 200), in accordance with illustrativeembodiments.

Referring to FIGS. 8A and 8B in conjunction with FIG. 8C now, the bottomportion 205 includes a lower section 215 having cutouts 220 thataccommodate arms 225 (only two of which are visible in FIG. 8C) of thetop portion 210. Likewise, in some embodiments, upper section 230 of thetop portion 210 includes cutouts 235 that accommodate arms 240 of thebottom portion 205. In some embodiments, the shape and size of thecutouts 220 and the cutouts 235 may be varied to correspond to the shapeand size of the arms 225 and the arms 240. In some embodiments, theshape and/or size of the cutouts 220 may be different from the shapeand/or size of the cutouts 235 to correspond to the varying shape and/orsize of the arms 225 and the arms 240. Further, although six of the arms225 and six of the arms 240 have been shown in the present disclosure,in other embodiments, greater than or fewer than six arms may be usedfor each of the arms 225 and the arms 240. The number of the cutouts 220and the cutouts 235 may vary based upon the number of the arms 225 andthe arms 240, respectively, that those cutouts are configured toreceive.

Furthermore, in at least some embodiments, grooves 245 may be providedon the bottom portion 205. The grooves 245 may be provided on the lowersection 215, bordered by walls 250 and 255 that project outwards fromthe lower section. In contrast to the grooves 170 that extend the entire(or substantially entire) length of the expandable cage 100, the grooves245 are configured to extend only a portion of the length of theexpandable cage 200. Specifically, as shown in FIGS. 8A and 8B, thegrooves 245 on each side of the expandable cage 200 include two groovesseparated by the cutouts 220. The grooves 245 may be used to receiveshims, as discussed above, for expanding the height of the expandablecage 200 upon assembly. The expandable cage 200 also includes an opening260, which is similar to the opening 150, and configured to receive abone graft promoting material. The shape, size, and other configurationof the opening 260 may vary from one embodiment to another, and in someembodiments, the opening may be absent.

By virtue of using the cutouts 220 and the cutouts 235, maximalcontraction of the expandable cage 200 may be achieved, such that theoverall height of the expandable cage is further reduced (compared tothe maximally contracted height of the expandable cage 100), therebyfacilitating easier insertion of the expandable cage into the spinalcavity. The cutouts 220 and the cutouts 235 also reduce the amount ofmaterial that is used for constructing the expandable cage 200, therebyreducing the overall cost of manufacturing the expandable cage.

Turning now to FIGS. 9A and 9B, assembly of the expandable cage 200 isdepicted, in accordance with at illustrative embodiment. Specifically,FIG. 9A shows the expandable cage 200 in an engaged position prior toshim insertion, while FIG. 9B shows the expandable cage in the engagedposition with the shims inserted. As shown in FIGS. 9A and 9B, the topportion 210 is configured to engage or mate with the bottom portion 205.Specifically, in some embodiments, the arms 225 of the top portion 210are received within the cutouts 220, and the arms 240 are receivedwithin the cutouts 235 to facilitate engagement of the top portion withrespect to the bottom portion. Further, the grooves 245 are designed toaccommodate shims 265 and 270 (See FIG. 9B). The configuration of FIG.9A shows the top portion 210 of the expandable cage 200 assembled to thebottom portion 205 thereof, but without the assembly of the shims 265and 270, while FIG. 9B shows the shims assembled within the expandablecage.

Thus, FIG. 9B shows a perspective view of the expandable cage 200, nowwith the addition of the shims 265 and 270, in accordance with anillustrative embodiment. The top portion 210 is shown as engaging ormated with the bottom portion 205. In some embodiments, the grooves 245accommodate the shims 265 and 270. In some embodiments, the shims 265and 270 sit within the grooves 245, such that an inferior-most surface(e.g., a bottom surface) of the shims 265 and 270 rests on thesuperior-most surface (e.g., a top surface) of the lower section 215 ofthe bottom portion 205. In turn, the inferior-most surface (e.g., abottom surface) of the arms 225 of the top portion 210 rest on asuperior-most surface (e.g., a top surface) of the shims 265 and 270,thus, holding the expandable cage 200 in a mechanically stable expandedconfiguration. It is to be understood that although each of the grooves245 are configured as two smaller grooves separated by the cutouts 220,in some embodiments, the shims 265 and 270 may be configured to span theentire (or substantially entire length of the bottom portion 205. Inother embodiments, smaller shim portions of the shims 265 and 270spanning only the length of each respective one of the grooves 245 maybe used.

Furthermore, in some embodiments, the arms 225 of the top portion 210may be configured to articulate via a hinge or similar rotatorycomponent relative to the upper section 230 of the top portion.Likewise, the arms 240 of the bottom portion 205 may be configured toarticulate relative to the lower section 215 of the bottom portion. Byarticulating the arms 225 and the arms 240, shims (e.g., the shims 265and 270) of different heights anteriorly and posteriorly may be placed,thereby resulting in an expandable cage (e.g., the expandable cage 200)with a taller height anteriorly than posteriorly, or a taller heightposteriorly than anteriorly, which may result in the expandable cageassuming a lordotic or kyphotic configuration. Such a configuration mayin turn enable a surgeon to control, to some degree, a patient'ssagittal alignment during an operation.

Turning now to FIG. 10, a perspective view of the expandable cage 200 ina maximally contracted position is shown, in accordance with anillustrative embodiment. The top portion 210 is shown engaging or matingwith the bottom portion 205. In some embodiments, and as discussedabove, the lower section 215 of the bottom portion 205 includes thecutouts 220 that accommodate the arms 225 of the top portion 210.Likewise, the cutouts 235 accommodate the arms 240 of the bottom portion205. The cutouts 220 and 235 serve the purpose of allowing theexpandable cage 200 to contract or collapse to a shortest possibleheight, H3, which facilitates surgical insertion, for example, into arelatively collapsed intervertebral disk space. In comparison to theexpandable cage 100, the expandable cage 200 allows for a greater heightcontraction.

Specifically, referring back to FIG. 2 above, when the top portion 105mates with the bottom portion 110 of the expandable cage 100, in amaximally contracted position, the inferior-most surface (e.g., a bottomsurface) of the arms 125 and 130 come into contact with thesuperior-most surfaces (e.g., a top surface) of the outward projections155, as well as the end projections 175. Likewise, the superior-mostsurfaces (e.g., a top surface) of the arms 140 and 145 contact theinferior-most surface (e.g., the bottom surface 120) of the top portion105, thus limiting the amount of maximal contraction of the expandablecage 100. By virtue of providing the cutouts 220 and 235 in theexpandable cage 200, the arms 225 and 240, respectively, are not limitedby the outward projections 155, 160, thereby enabling the expandablecage 200 to achieve a smaller height profile compared to the expandablecage 100.

Referring now to FIG. 11, a perspective view of a bottom portion 275 andan alternative embodiment of a top portion 280 of a lateralextrinsically expandable cage (e.g., expandable cage 285) is shown, inaccordance with an illustrative embodiment. To the extent that theexpandable cage 285 is similar to the expandable cage 100, only thedifferences are described herein. The top portion 280 includes arms 290that are configured as outward projections from a bottom surface 295 ofthe top portion. In some embodiments, the arms 290 are configured as asingle continuous piece of material that runs the length L3 of the topportion 280. The bottom portion 275 is similar in configuration to thebottom portion 110, and is therefore, not described here again.

In some alternative embodiments, the arms 290 may articulate via a hingeor similar rotatory component relative to the bottom surface 295 of thetop portion 280. In this manner, shims (not shown, depicted later inFIGS. 12B and 12C) of different heights may be placed to result in anexpandable cage (e.g., the expandable cage 285) with a taller heightanteriorly than posteriorly, or a taller height posteriorly thananteriorly, which in turn may result in the expandable cage assuming alordotic or kyphotic configuration. Such a configuration may enable thesurgeon to control, to some degree, a patient's sagittal alignment.

Turning now to FIGS. 12A-12C, perspective views depicting the topportion 280 and the bottom portion 275 in the expandable cage 285 areshown, in accordance with illustrative embodiments. Specifically, FIG.12A is a perspective view depicting the top portion 280 and the bottomportion 275 of the expandable cage 285, with the top portion mated to orengaging with the bottom portion before the insertion of the shims, inaccordance with an illustrative embodiment. The grooves 170 on thebottom portion 275 are configured to receive the shims to hold theexpandable cage 285 in the expanded configuration. FIG. 12B is aperspective view depicting the top portion 280 and the bottom portion275 of the expandable cage 285 as shown in FIG. 12A, but with shims 300and 305 inserted into the grooves 170, in accordance with anillustrative embodiment. In some embodiments, upon insertion of theshims 300 and 305, the inferior-most surface (e.g., a bottom surface) ofthe arms 290 rests on the superior-most surface (e.g., a top surface) ofthe shims 300 and 305 along the entire length of said surfaces, thusholding the expandable cage 285 in an expanded configuration.

FIG. 12C is a side perspective view depicting the top portion 280 andthe bottom portion 275 of the expandable cage 285 with the shims 300 and305 inserted, as shown in FIG. 12B, in accordance with an illustrativeembodiment. Again, in some embodiments, the inferior-most surface (e.g.,a bottom surface) of the arms 290 rests on the superior-most surface(e.g., a top surface) of the shims 300 and 305 along the entire lengthof said surfaces, thus holding the expandable cage 285 in an expandedconfiguration. Upon assembly, the shim 305 may be the anterior shim, andthe shim 300 may be the posterior shim, or vice-versa. In someembodiments, the shims 300 and 305 are of identical height, resulting ina final overall cage height that is the same both anteriorly andposteriorly, thereby resulting in a level or parallel cage.

Referring back to the description of an alternative embodiment with ahinged articulation between the arms 290 relative to the bottom surface295 of the top portion 280, as described in FIG. 11 above, it may bepossible to place a shim (e.g., the shim 305) that is of a differentheight than the other shim (e.g., the shim 300). If the shim 305 istaller in height than the shim 300, the expandable cage 285 is alordotic cage. If the shim 300 is taller in height than the shim 305,the expandable cage 285 is a kyphotic cage. A surgeon may use differentshim heights to produce a lordotic or kyphotic lateral extrinsicallyexpandable cage of differing sagittal dimensions, which would allow thesurgeon to control, to some degree, a patient's sagittal alignmentduring an operation. In an alternative embodiment, the tolerance betweenthe arms 290, 140, and 145 may be designed such that different shimheights may produce a lordotic or kyphotic cage in the absence of ahinge or other articulation between the arms and the upper or bottomsections of the cage.

Turning now to FIG. 13, a perspective view depicting an alternativeembodiment of an expandable cage 310 is shown, in accordance with anillustrative embodiment. The expandable cage 310 is similar to theexpandable cage 100, the expandable cage 200, and the expandable cage285. The expandable cage 310 also includes two threaded holes 315 on asidewall 320 of top portion 325 that correspond with two threaded holes330 on a sidewall 335 on a bottom portion 340. The threaded holes 315and 330 are configured to attach to a cage insertion and expansiondevice (not shown) for keeping the top portion 325 in an expandedposition relative to the bottom portion 340 until the shims (not shown)are inserted. Although only two of the threaded holes 315 and 330 areshown, in some embodiments, there may be more or fewer number of holesin the top portion 325 and the bottom portion 340. Further, the threadedholes 315 and 330 may or may not be threaded. Rather, otherconfigurations may be used to attach the expandable cage 310 to a cageinsertion and expansion device (not shown). Moreover, the location ofthe threaded holes 315 and 330 may vary in other embodiments. Forexample, in some embodiments, the threaded holes 315 may be located atany point(s) along the sidewall 320 of the top portion 325 and thethreaded holes 330 may correspondingly be placed on the sidewall 335 ofthe bottom portion 340. In some embodiments, the threaded holes 315 and330 may be provided on other parts of the expandable cage 310 forattaching the cage insertion and expansion device. In some embodiments,the means of attachment of a cage insertion and expansion device may beintegrated with the expandable cage 310, and may be comprised of anydesign that allows for attachment of the cage insertion and expansiondevice. In some embodiments, the insertion device may be separate fromthe expansion device.

Turning now to FIG. 14A, a perspective view depicting the expandablecage 310 and an insertion and expansion device 400 is shown, inaccordance with illustrative embodiments. As discussed above withrespect to FIG. 13, in some embodiments, the expandable cage 310includes the threaded holes 315 on the sidewall 320 of the top portion325. The threaded holes 315 correspond with the threaded holes 330 onthe sidewall 335 on the bottom portion 340. The threaded holes 315 andthe threaded holes 330 are configured to attach to the cage insertionand expansion device 400 for keeping the top portion 325 in an expandedposition or configuration relative to the bottom portion 340 until theshims (not shown) are inserted. In some embodiments, the insertion andexpansion device 400 includes an upper handle 405 that joins at an angleto arm 410, which in turn is connected to arm 420 via hinge 415. Theinsertion and expansion device also includes a lower handle 435 thatjoins at an angle to arm 445, which in turn is connected to arm 455 viahinge 450. In some embodiments, the upper handle 405 articulatesrelative to the lower handle 435 via a hinge 440. In some embodiments,the arm 420 includes a part 425 that has a face 426 that faces away fromthe expandable cage 310 and towards the surgeon, and an opposite face(not shown) that faces towards the expandable cage and may be configuredto press against the sidewall 320 of the top portion 325 of theexpandable cage. Likewise, the arm 455 includes a part 460 that has aface 461 that faces away from the expandable cage 310 and towards thesurgeon, and an opposite face (not shown) that faces away from thesurgeon and may be configured to press against the sidewall 335 of thebottom portion 340 of the expandable cage.

The pressing together of the insertion and expansion device 400 againstthe expandable cage 310 facilitates attachment of the insertion andexpansion device to the expandable cage, as described below in moredetail. In some embodiments, the part 425 includes holes 430 that arepositioned in line with the threaded holes 315, and the part 460includes holes 465 that are positioned in line with the threaded holes330. The holes 430 and 465 are used to attach the insertion andexpansion device 400 to the expandable cage 310, as discussed in greaterdetail in FIGS. 14B-14G. In some embodiments, the arm 420 may include anextension 475 and the arm 455 may include an extension 470. In someembodiments, the extensions 470 and 475 may fit within the expandablecage 310 and be employed to assist in the expansion of the expandablecage, as discussed in greater detail in FIGS. 14B-14F.

Turning now to FIG. 14B and FIG. 14C, perspective views depicting theattachment of the insertion and expansion device 400 to the expandablecage 310 are shown, in accordance with illustrative embodiments.Specifically, FIG. 14B depicts the insertion and expansion device 400sitting flush against the expandable cage 310, for receiving fasteners480 through the holes 430 of the insertion and expansion device and thethreaded holes 315 (not shown) of the expandable cage, as well asthrough the holes 465 of the insertion and expansion device and thethreaded holes 330 (not shown) of the expandable cage. The fasteners 480secure the insertion and expansion device 400 to the expandable cage310. In some embodiments, the fasteners 480 include a threaded portion481 which threads into the threaded holes 315 and 330 (See FIG. 14A) ofthe expandable cage 310, a collar 482 that presses or abuts against thepart 425 and part 460 as the threaded portion 481 is advanced into thethreaded holes 315 and 330 (Again, See FIG. 14A), and in so doingpresses the part 425 and the part 460 tightly against the reciprocalsidewalls of the expandable cage 310. In some embodiments, the fasteners480 include a shaft 483, and a terminal shaft portion 484 thatcorresponds to the configuration of a screwdriver or other similarinsertion device (not shown) used to insert the fasteners 480 throughthe holes 430 and 465 and into the threaded holes 315 and 330.

FIG. 14C depicts the fasteners 480 having been inserted into the holes430 and 465 of the insertion and expansion device 400 and threaded intothe threaded holes 315 and 330 of the expandable cage 310, thus securingthe insertion and expansion device to the expandable cage. Upon securingthe insertion and expansion device 400 to the expandable cage 310, theexpandable cage is now ready for insertion into the spine during thefusion operation. In some embodiments, four of the fasteners 480 areused, while in other embodiments, more or fewer fasteners may be used.Furthermore, in some embodiments, the configuration of the fasteners 480may vary. For example, in some embodiments, one or more of the fasteners480 need not be threaded. Rather, the fasteners 480 may be configured toattach the insertion and expansion device 400 to the expandable cage 310via an interference fit or another connecting mechanism. Likewise, insome embodiments, the fasteners 480 need not always include one or moreof the threaded portion 481, the collar 482, the shaft 483, and theterminal shaft portion 484. Rather, the fasteners 480 may be configuredwith greater, fewer or other components than those described herein.Additionally, in some embodiments, fastening mechanisms other than thefasteners 480 may be used for securing the insertion and expansiondevice 400 to the expandable cage 310. Once the expandable cage 310 isinserted into the spine and expanded to the desired height, and shimsplaced to hold the expandable cage in its expanded configuration, thefasteners 480 are removed. By removing the fasteners 480, the insertionand expansion device 400 may be disengaged from the expandable cage 310,such that the insertion and expansion device can be removed from thesurgical area.

FIG. 14D is a close-up view of FIG. 14B, depicting a partial perspectiveview of the insertion and expansion device 400, and the expandable cage310, in accordance with illustrative embodiments. In some embodiments,the holes 465 and 430 accommodate the fasteners 480 (a single instanceof the fasteners 480 is shown here, but in this embodiment, fourfasteners would be used, one for each of the holes 465 and 430). In someembodiments, the fasteners 480 are inserted through the holes 465 andinto the threaded holes 330 of the expandable cage 310. Likewise, thefasteners 480 can be inserted through the holes 430 and into thethreaded holes 315 of the expandable cage 310. As the fasteners 480 aretightened, the insertion and expansion device 400 is tightly pressedagainst the expandable cage 310, thus providing a rigid connectionbetween the expandable cage and the insertion and expansion device. Thisallows the surgeon to insert the expandable cage 310 into the spine andexpand the expandable cage to the desired height, prior to adding theshims (not shown). In some embodiments, the insertion and expansiondevice 400 includes the extension 470 and the extension 475 (partiallyshown). In some embodiments, the extensions 470 and 475 pass intoexpandable cage 310 and rest flush against the top and bottom portionsof the expandable cage.

For example, as shown in FIG. 14D, the extension 470 is shown restingflush against an upward-facing (i.e., towards the patient's head)surface of the bottom portion 340 of the expandable cage 310, whereasthe extension 475, which is only partially shown, is resting flushagainst the downwards-facing (i.e., towards the patient's feet) surfaceof the top portion 325 of the expandable cage 310. In some embodiments,the extensions 470 and 475 extend partially into the expandable cage310, whereas in alternative embodiments, those extensions may extendalong the entire length of the expandable cage. When the expandable cage310 is inserted into the desired position in the spine during surgery,the insertion and expansion device 400 is used to expand the expandablecage to an extended configuration, and the extensions 470 and 475 assistin this expansion maneuver. Specifically, the extension 470 pressesdownwards on the upward-facing surface of the bottom portion 340 and theextension 475 presses upwards on the downwards-facing surface of the topportion 325, thus pressing the top portion away from the bottom portion,and facilitating expansion of the expandable cage 310 in a verticaldirection. In some embodiments, the extensions 470 and 475 extend intothe expandable cage 310 and serve as the primary connection between theinsertion and expansion device 400 and the expandable cage 310, withoutrelying on the fasteners 480. In some embodiments, the part 460 of thearm 455 includes a groove 476 that lines up with the grooves 170 (SeeFIGS. 1C, 2, 5A) of the expandable cage 310. When the expandable cage310 is inserted into the spine during surgery and expanded using theinsertion and expansion device 400, the shims are inserted into thegrooves 170 (only one groove is visible in FIG. 14D) to hold theexpandable cage in the expanded configuration. In some embodiments, thegrooves 476 may be used by the surgeon to guide the shims into thegrooves 170.

Turning now to FIG. 14E, a top perspective view of the expandable cage310, the insertion and expansion device 400, and the fasteners 480 areshown in an assembling position, in accordance with illustrativeembodiments. Specifically, FIG. 14E depicts the expandable cage 310separate from the insertion and expansion device 400, with the fasteners480 not yet securing the insertion and expansion device to theexpandable cage. Referring to FIG. 14F, a top perspective view of theexpandable cage 310, the insertion and expansion device 400, and thefasteners 480 are shown in an assembled position, with the fastenerssecuring the insertion and expansion device to the expandable cage.

Turning now to FIG. 14G and FIG. 14H, side perspective views of theexpandable cage 310 attached to the insertion and expansion device 400with the fasteners 480 are shown, in accordance with illustrativeembodiments. In some embodiments, the insertion and expansion device 400includes the upper handle 405 and the lower handle 435. FIG. 14G depictsthe expandable cage 310 in its collapsed configuration, corresponding toan overall cage height H4, in which case the terminal ends (i.e.,furthest from the expandable cage) of the upper handle 405 and the lowerhandle 435 are at their furthest distance from each other, representedby distance H4 a in FIG. 14G. FIG. 14H depicts the expandable cage 310in an expanded configuration, corresponding to overall cage height H5,in which case the terminal ends (i.e., furthest from the expandable cage310) of the upper handle 405 and the lower handle 435 are closer to eachother when compared to the distance H4 a in FIG. 14G; this distance isshown as H5 a. The height of the expandable cage 310 is, thus,adjustable—the closer the terminal ends of the upper handle 405 and thelower handle 435 are to each other, the taller (e.g., cage height) theexpandable cage is, with the cage height expansion vertically within thelimits of the cage component parameters.

Turning now to FIG. 15A, a side or lateral view of a lumbar spinesegment 500 is shown, in accordance with an illustrative embodiment. Thelumbar spine segment 500 includes a cephalad vertebra 505, a caudalvertebra 515, and an intervertebral disk space 510. The expandable cage100 is inserted into in the intervertebral disk space 510 after adiskectomy has been performed. As depicted in FIG. 15A, the expandablecage 100 is in a contracted or collapsed position. Although theexpandable cage 100 is depicted in FIG. 15A as having certaindimensions, it is to be understood that in other embodiments, thedimensions of the expandable cage may vary based upon the size of theintervertebral disk space 510. For example, as depicted in FIG. 15A,although the expandable cage 100 does not cover the entire space of theintervertebral disk space 510, in other embodiments, the expandable cage100 may be configured to be larger or smaller than depicted. Forexample, in some embodiments, the expandable cage 100 may vary indimensions in either or both of the anterior-posterior andmedial-lateral dimensions.

Turning now to FIG. 15B, a side or lateral view of the lumbar spinesegment 500 is shown, in accordance with an illustrative embodiment. Thelumbar spine segment 500 of FIG. 15B includes the cephalad vertebra 505,the caudal vertebra 515, and the intervertebral disk space 510. However,in contrast to the configuration of FIG. 15A, which depicted theexpandable cage 100 in a contracted configuration, FIG. 15B depicts theexpandable cage in an expanded configuration. The expansion of theexpandable cage 100 increases the height of the intervertebral diskspace 510, as the top portion 105 of the expandable cage is pushedagainst the cephalad vertebra 505 in a cephalad direction and the bottomportion 110 of the expandable cage is pushed against the caudal vertebra515 in a caudal direction.

Referring now to FIG. 15C, the expandable cage 100 is shown in anexpanded position as seen in FIG. 15B, now with the shims 195 insertedinto the expandable cage and holding the expandable cage in an expandedposition. The lumbar spine segment 500, as depicted, includes thecephalad vertebra 505, the caudal vertebra 515, and the intervertebraldisk space 510. The shims 195 hold the expandable cage 100 in anexpanded position, which results in an increase in the height of theintervertebral disk space 510.

Turning now to FIG. 16, a front or anterior view of the lumbar spinesegment 500 is shown, in accordance with an illustrative embodiment. Thelumbar spine segment 500 includes the cephalad vertebra 505, the caudalvertebra 515, and the intervertebral disk space 510, as discussed above.A front or anterior view of the expandable cage 100 is depicted in theintervertebral disk space 510, after a diskectomy has been performed tosufficient extent that the expandable cage can be inserted into theintervertebral disk space. Disk annulus 511 is depicted having beenpartially or completely removed during the diskectomy process, prior toinsertion of the expandable cage 100. The expandable cage 100 isdepicted in a relatively contracted configuration, for example, in asimilar configuration as shown in FIG. 15A. The expandable cage 100 maybe expanded to the expanded configuration of FIGS. 15B-C. Further, asdiscussed above, the dimensions of the expandable cage 100 may be variedas desired based upon the size of the intervertebral disk space 510. Forexample, the expandable cage 100 may be longer or shorter in themedial-to-lateral dimension.

Turning now to FIG. 17, a flow chart outlining a process 545 forperforming a lumbar spine lateral fusion using a lateral extrinsicallyexpandable cage (e.g., the expandable cage 100, 200, 285, and 310) isshown, in accordance with an illustrative embodiment. In alternativeembodiments, fewer, additional, and/or different operations may beperformed, including thoracic fusions. In an operation 550, a surgeonperforms a lateral or anterolateral approach, or alternative approach,to the lumbar spine in a fashion known to those of skill in the art. Inan operation 555, a diskectomy is performed in preparation for a fusion.In an operation 560, depending on the patient anatomy and the surgicalapproach, an expandable cage (e.g., the expandable cage 100, 200, 285,310) is chosen to accommodate the anatomy. The top and bottom parts ofthe expandable cage (e.g., the expandable cage 100, 200, 285, 310) mateor engage with each other and may slide vertically, but are constrainedin the anterior-posterior and medial-lateral planes, allowing for cageheight expansion vertically within the limits of the cage componentparameters. In an operation 565, the insertion and expansion device isattached to the expandable cage (e.g., the expandable cage 100, 200,285, 310). The insertion and expansion device may rest between the topand bottom parts of the cage, or may be attached to the expandable cagevia holes (e.g., the holes 315, 330) in the top and bottom portions ofthe cage, or a combination thereof. In the operation 565, the expandablecage is then inserted into the intervertebral disk space to be fused. Inan operation 570, the expandable cage is expanded to the desired heightwith the insertion and expansion device, and shims corresponding to theselected height are slid into the grooves in the bottom portion of theexpandable cage. The shims are configured to hold the expandable cage inan expanded position. In an operation 575, the insertion and expansiondevice is removed and the expandable cage is packed with bone growthpromoting material such as bone graft and/or bone graft substitute, andthe surgeon completes the fusion procedure in a manner known to those ofskill in the art.

In an alternative embodiment, some or all of the bone growth promotingmaterial may be placed in the expandable cage prior to insertion. In analternative embodiment, the process 545 may be used for a thoracic orthoracolumbar or lumbosacral fusion using the expandable cage (e.g., theexpandable cage 100, 200, 285, 310). Upon completion of the procedure,the surgical instruments and non-implanted components of the lateralextrinsically expandable cage are removed from the surgical site and theincision is closed.

Thus, the present disclosure provides an extrinsically expandable lumbarspine fusion cage that includes top and bottom portions that mate witheach other, and are free to move with respect to each other in acephalad-caudal (i.e., vertical) direction, thereby expanding orcontracting an overall cage height. The top and bottom portions areconstrained from moving with respect to each other in anterior-posteriorand medial-lateral planes. Cage expansion occurs via an insertion andexpansion device that is not part of the cage itself, but attaches tothe cage. The cage is inserted into the intervertebral disk space to befused after a diskectomy is performed. After insertion, the cage isexpanded to a desired height. Once the cage is expanded and the top andbottom portions of the cage are pressed firmly against the adjacentvertebral endplates by virtue of the presence of the cage within thedisk space, the cage is held in the expanded position by arms thatextend outwardly from the top and bottom portions. The top arms rest onshims that are inserted into grooves in the bottom portion of the cage,the shims in turn resting on a lower section of the bottom portion ofthe cage. Once the insertion and expansion device is removed, the topand bottom portions of the cage are held in the expanded position by theshims, and collectively the top and bottom parts of the cage and theshims comprise the lateral extrinsically expandable cage. Shims may bemade in different sizes in order to hold the cage in various expandedheights and configurations. Once the shims are inserted and theinsertion and expansion device removed, a bone growth promotingsubstance such as bone graft and/or bone graft substitute may be placedwithin the cage to provide the biological component of the fusionoperation. Thus, the cage provides structural support to the spinebetween adjacent vertebral bodies to be fused.

In some embodiments, the shims may be contained within grooves in thetop or bottom portions of the cage, or in some embodiments the shims maynot be contained within grooves. In some embodiments, the cage may bedesigned to accommodate shims of different heights, such as with ananterior shim taller than a posterior shim, or a posterior shim tallerthan an anterior shim, thus allowing for in-situ modulation of thesagittal cage configuration, which in turn affects the degree oflordosis or kyphosis across the spinal segment that is receiving thecage. In some embodiments, a bone growth promoting substance such asbone graft or bone graft substitute may then be packed into the cage.

Thus, the present disclosure provides an extrinsically expandable cage,which is configured to be expanded using a removable insertion andexpansion device from outside of the spinal cavity. The insertion andexpansion device is not configured to be part of the expandable cageafter the insertion of the shims into the expandable cage. By virtue ofexpanding the expandable cage using an extrinsic mechanism that does notform a part of the final expandable cage, the present disclosureprovides an expandable cage that may achieve greater height expansionand contraction compared to conventional expandable cages. Further, byremoving the insertion and expansion device from the expandable cage,the insertion and expansion devices does not take up any unnecessaryspace within the expandable cage, which may then be used to fill inadditional bone graft promoting material. The cost and complexity of theexpandable cage is also reduced.

In some embodiments, part of the expandable cage design may include anexpansion limiter such that the expandable cage may not beover-expanded, which may result in disengagement of the top portion ofthe expandable cage from the bottom portion of the expandable cage. Insome embodiments, the lateral extrinsically expandable cage may includeblocking mechanisms to ensure the shims remain confined within theexpandable cage. In some embodiments, part of the expandable cage designmay also include an optional device that may be inserted and attachedonto a lateral wall of the expandable cage opposite the insertion deviceto prevent the bone growth promoting substance from extruding throughthe opening of the expandable cage that is opposite the insertion andexpansion device. In some embodiments, a cage insertion device may beseparate from a cage expansion device. An insertion and expansion devicemay be used that rests in part between the top and bottom portions ofthe expandable cage, or that attaches to a lateral aspect of theexpandable cage, and is used to insert the expandable cage into theintervertebral space to be fused and then extrinsically expand theexpandable cage to the desired height, and later removed in theirentirety after shim placement.

The components (e.g., the top portion, bottom portion, shims) describedherein may be made in a variety of lengths and/or shapes to accommodatevarious patient anatomies and surgeon preferences. The components can bemade from a variety of biologically compatible materials suitable formedical applications, including but not limited to metals, bonematerial, ceramics, and synthetic composites. For example, thecomponents of a lateral extrinsically expandable cage may be fabricatedfrom materials such as titanium, titanium alloys, cobalt-chrome alloys,stainless steel, stainless steel alloys, thermoplastics such aspolyether ether ketone (PEEK) and other similar substances, carbonfiber, carbon fiber composites, ceramics and composites, aluminum,allograft bone, xenograft bone, any combination of the above substances,or any suitable material that is able to withstand the biomechanicalstresses under which they are placed.

The exemplary embodiments of the surgical system and related methods arediscussed in terms of medical devices used for the treatment of spinaldisorders. In some embodiments, the systems and methods of the presentdisclosure are employed with a spinal fusion, for example, with athoracic, lumbar and/or sacral region of the spine.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely examples, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable,” to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations.

However, the use of such phrases should not be construed to imply thatthe introduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation containing only one such recitation, even when the same claimincludes the introductory phrases “one or more” or “at least one” andindefinite articles such as “a” or “an” (e.g., “a” and/or “an” shouldtypically be interpreted to mean “at least one” or “one or more”); thesame holds true for the use of definite articles used to introduce claimrecitations. In addition, even if a specific number of an introducedclaim recitation is explicitly recited, those skilled in the art willrecognize that such recitation should typically be interpreted to meanat least the recited number (e.g., the bare recitation of “tworecitations,” without other modifiers, typically means at least tworecitations, or two or more recitations).

Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, and C”would include but not be limited to systems that have A alone, B alone,C alone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). In those instances where a conventionanalogous to “at least one of A, B, or C, etc.” is used, in general sucha construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, or C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.).

It will be further understood by those within the art that virtually anydisjunctive word and/or phrase presenting two or more alternative terms,whether in the description, claims, or drawings, should be understood tocontemplate the possibilities of including one of the terms, either ofthe terms, or both terms. For example, the phrase “A or B” will beunderstood to include the possibilities of “A” or “B” or “A and B.”Further, unless otherwise noted, the use of the words “approximate,”“about,” “around,” “substantially,” etc., mean plus or minus tenpercent.

The foregoing description of illustrative embodiments has been presentedfor purposes of illustration and of description. It is not intended tobe exhaustive or limiting with respect to the precise form disclosed,and modifications and variations are possible in light of the aboveteachings or may be acquired from practice of the disclosed embodiments.It is intended that the scope of the disclosure be defined by the claimsappended hereto and their equivalents.

What is claimed is:
 1. An expandable cage system for use in spinalsurgery, the expandable cage system comprising: an expandable cage,wherein the expandable cage comprises: a top portion having an outwardlyextending top arm; a bottom portion having an outwardly extending bottomarm; wherein the bottom arm is configured to engage with the top armsuch that, upon engagement, the top portion and the bottom portion aresubstantially restricted from movement relative to each other in ananterior-posterior direction and in a medial-lateral direction; andwherein the top portion has a first outward facing side and the bottomportion has a second outward facing side, each of the first outwardfacing side and the second outward facing side comprising a first set ofone or more holes, each of the one or more holes configured to receive afastener.
 2. The expandable cage system of claim 1, further comprising aremovable shim configured to be positioned between the top portion andthe bottom portion to hold the expandable cage system in an expandedposition within a spinal cavity.
 3. The expandable cage system of claim2, wherein the removable shim comprises a first shim and a second shim,and wherein the bottom portion comprises: a first groove configured toreceive the first shim, and a second groove configured to receive thesecond shim, wherein the first shim and the second shim are configuredto hold the top portion in the expanded position relative to the bottomportion when positioned within the first groove and the second groove,respectively.
 4. The expandable cage system of claim 3, wherein each ofthe first groove and the second groove includes an end projectionconfigured to restrict motion of the first shim in the first groove andthe second shim in the second groove.
 5. The expandable cage system ofclaim 3, wherein a height of the first shim is the same as a height ofthe second shim.
 6. The expandable cage system of claim 1, wherein thetop arm includes a first set of top arms and a second set of top arms,and wherein the bottom arm includes: a first set of bottom armsconfigured to engage with the first set of top arms, and a second set ofbottom arms configured to engage with the second set of top arms.
 7. Theexpandable cage system of claim 6, wherein the top portion includes afirst slot adjacent to each of the first set of top arms and a secondslot adjacent to each of the second set of top arms, such that the firstset of bottom arms is configured to be received within the first slot,and the second set of bottom arms is configured to be received withinthe second slot.
 8. The expandable cage system of claim 7, wherein thefirst set of top arms includes a first top arm and a second top arm, andwherein each of the first top arm and the second top arm extends alongsubstantially an entire length of the top portion.
 9. The expandablecage system of claim 6, wherein the first set of top arms and the secondset of top arms each comprises a first top arm, a second top arm, and athird top arm; wherein the first set of bottom arms and the second setof bottom arms each comprise a first bottom arm, a second bottom arm,and a third bottom arm; wherein the third bottom arm and the third toparm each comprise a slot; and wherein the third bottom arm is configuredto be received within the slot of the third top arm.
 10. The expandablecage system of claim 1, further comprising an expansion deviceconfigured to adjust a height of the expandable cage.
 11. The expandablecage system of claim 10, wherein the expansion device comprises: anupper handle having a first upper end and a second upper end, whereinthe first upper end is configured to connect to an upper extension; alower handle having a first lower end and second lower end, wherein thefirst lower end is configured to connect to a lower extension; a middlejoint located a first distance from the first lower end and a seconddistance from the first upper end, wherein the upper handle isconfigured to articulate relative to the lower handle at the middlejoint via a hinge; the upper extension having a first upper portion anda second upper portion, wherein the first upper portion is configured toconnect to the first upper end of the upper handle via an upper joint,and wherein the upper extension is configured to articulate relative tothe upper handle at the upper joint; and the lower extension having afirst lower portion and a second lower portion, wherein the first lowerportion is configured to connect to the first lower end of the lowerhandle via a lower joint, and wherein the lower extension is configuredto articulate relative to the lower handle at the lower joint.
 12. Theexpandable cage system of claim 11, wherein the second upper portion ofthe upper extension comprises one or more upper side projections and thesecond lower portion of the lower extension comprises one or more lowerside projections, and wherein the upper side projections and the lowerside projections each extend in a direction parallel to the firstoutward facing side and the second outward facing side.
 13. Theexpandable cage system of claim 11, further comprising one or morefasteners.
 14. The expandable cage system of claim 13, wherein a firstside of each of the upper and lower side projections comprises a secondset of one or more holes, wherein a depth of the second set of one ormore holes is the same as a width of the side projections and the secondset of one or more holes is compatible with the one or more fasteners.15. The expandable cage system of claim 14, wherein the one or morefasteners are individually inserted through each of the second set ofone or more holes in the first side of each of the upper sideprojections and lower side projections of the expansion device andthrough the corresponding first set of one or more holes in the firstoutward facing side and the second outward facing side, to join theexpansion device to the expandable cage and facilitate secure insertionof the expandable cage into the spinal cavity.
 16. The expandable cagesystem of claim 14, wherein the upper extension and lower extension ofthe expansion device are each configured to pass into the expandablecage such that an upper surface of the upper extension of the expansiondevice rests against a bottom surface of the top portion of theexpandable cage and a lower surface of the lower extension of theexpansion device rests against a top surface of the bottom portion ofthe expandable cage.
 17. The expandable cage system of claim 1, whereineach of the top portion and the bottom portion comprises an openingconfigured to receive a bone graft promoting material.
 18. An expandablecage system for use in spinal surgery, the expandable cage systemcomprising: an expandable cage, wherein the expandable cage comprises: atop portion having an outwardly extending top arm; a bottom portionhaving an outwardly extending bottom arm, wherein the bottom arm isconfigured to engage with the top arm such that upon engagement, the topportion and the bottom portion are substantially restricted frommovement relative to each other in an anterior-posterior direction andin a medial-lateral direction; a removable shim configured to beselectively positioned between the top portion and the bottom portion tohold the expandable cage system in an expanded position within a spinalcavity; an expansion device configured to adjust a height of theexpandable cage; and one or more removable fasteners configured to jointhe expansion device to the expandable cage.
 19. The expandable cagesystem of claim 18, wherein the expansion device comprises: an upperhandle having a first upper end and a second upper end, wherein thefirst upper end is configured to connect to an upper extension; a lowerhandle having a first lower end and second lower end, wherein the firstlower end is configured to connect to a lower extension; a middle jointlocated a first distance from the first lower end, and a second distancefrom the first upper end, wherein the upper handle is configured toarticulate relative to the lower handle at the middle joint via a hinge;the upper extension having a first upper portion and a second upperportion, wherein the first upper portion is configured to connect tofirst upper end of the upper handle via an upper joint, and wherein theupper extension is configured to articulate relative to the upper handleat the upper joint; and the lower extension having a first lower portionand a second lower portion, wherein the first lower portion isconfigured to connect to the first lower end of the lower handle via alower joint, and wherein the lower extension is configured to articulaterelative to the lower handle at the lower joint.
 20. The expandable cagesystem of claim 18, wherein the removable shim comprises a first shimand a second shim, and wherein the bottom portion comprises: a firstgroove configured to receive the first shim, and a second grooveconfigured to receive the second shim, wherein the first shim and thesecond shim are configured to hold the top portion in the expandedposition relative to the bottom portion when positioned within the firstgroove and the second groove, respectively.